Rapid freezing of saturated clays under large thermal gradients

This study investigates the rapid freezing behavior of saturated clays under large thermal gradients. Although the freezing characteristics of soils under natural/low thermal gradients such as ice lens formation and water migration have been extensively studied, the freezing of a saturated soil under a large thermal gradient is not understood. This study presents rapid freezing tests to examine the freezing behavior of saturated fine-grained soils in a closed system under large thermal gradients using liquid nitrogen (LN). Temperatures are measured inside specimens during freezing and micro-CT visualized internally after freezing. Results show that large thermal gradients develop near the surfaces of specimens upon their submersion in LN. The specimens freeze homogeneously, and no visible ice lenses form, owing to the insufficient time for water migration and ice segregation under rapid freezing. The specimens fracture and split into major pieces, under no confining stresses in this study; freezing first occurs near the boundaries, and the freezing front propagates inward, creating temporal, differential volume changes between the outer and inner parts of the specimens, which leads to fractures in the unconfined state. The fractures affect subsequent temperature propagation and thermal gradients.

Possible role of intravenous administration of mesenchymal stem cells to alleviate interstitial cystitis/bladder pain syndrome in a Toll-like receptor-7 agonist-induced experimental animal model in rat

Background Interstitial cystitis/bladder pain syndrome (IC/BPS) categorized with and without Hunner lesions is a condition that displays chronic pelvic pain related to the bladder with no efficacious treatment options. There are strong associations suggested between Hunner-type IC and autoimmune diseases. Recently, we established an animal model of Hunner-type IC using a Toll-like receptor-7 (TLR7) agonist. Intravenous infusion of mesenchymal stem cells (MSCs) can be used to treat injury via multimodal and orchestrated therapeutic mechanisms including anti-inflammatory effects. Here, we investigated whether infused MSCs elicit therapeutic efficacy associated with the TLR7-related anti-inflammatory pathway in our Hunner-type IC model. Methods Voiding behaviors were monitored 24 h prior to the Loxoribine (LX), which is a TLR7 agonist instillation in order to establish a Hunner-type IC model (from − 24 to 0 h) in female Sprague–Dawley rats. LX was instilled transurethrally into the bladder. At 0 h, the initial freezing behavior test confirmed that no freezing behavior was observed in any of the animals. The LX-instilled animals were randomized. Randomized LX-instilled rats were intravenously infused with MSCs or with vehicle through the right external jugular vein. Sampling tissue for green fluorescent protein (GFP)-positive MSCs were carried out at 48 h. Second voiding behavior tests were monitored from 72 to 96 h. After the final evaluation of the freezing behavior test at 96 h after LX instillation (72 h after MSC or vehicle infusion), histological evaluation with H&E staining and quantitative real-time polymerase chain reaction (RT-PCR) to analyze the mRNA expression levels of inflammatory cytokines were performed. Results Freezing behavior was reduced in the MSC group, and voiding behavior in the MSC group did not deteriorate. Hematoxylin–eosin staining showed that mucosal edema, leukocyte infiltration, and hemorrhage were suppressed in the MSC group. The relative expression of interferon-β mRNA in the bladder of the MSC group was inhibited. Numerous GFP-positive MSCs were distributed mainly in the submucosal and mucosal layers of the inflammatory bladder wall. Conclusion Intravenous infusion of MSCs may have therapeutic efficacy in a LX-instilled Hunner-type IC rat model via a TLR7-related anti-inflammatory pathway.

Human freezing responses to virtual characters in immersive virtual reality are impacted by body expression, group affiliation and threat proximity

Social threat requires fast adaptive reactions. One prominent threat-coping behavior present in humans is freezing, of which heart rate deceleration and reduced postural mobility are two key components. Previous studies focused mainly on freezing reactions in rodents, but now virtual reality offers unique possibilities for controlled and ecologically valid lab-based experiments. Using immersive virtual reality, this study examined how several understudied aspects of social threat, i.e., emotional body expressions, group affiliation, and distance from the potential threat, affect freezing behavior in humans. Reduced heart rate and postural mobility were observed in participants when they faced aggressive-looking and proximal avatars. Freezing was also observed for ingroup aggression when participants were embodied in a black-skinned virtual body and faced black-skinned aggressive and proximal avatars. Our results, based on a highly ecological virtual reality paradigm, provide novel evidence on the social factors that elicit freezing behavior in humans.

Freezing or death feigning? Beetles selected for long death-feigning duration showed other tactics against different predators

Prey evolve anti-predator strategies against multiple enemies in nature. We examined how a prey species adopts different predation avoidance tactics against pursuit or sit-and-wait predators. As prey, we used two strains of Tribolium beetles artificially selected for short or long duration of death feigning. The results showed that, as prey, the short strains displayed the same behavior, escaping, against the two types of predators. On the other hand, death feigning is known to be effective for evading a jumping spider in the case of the long strains, while the present study showed that the long strain beetles used freezing behavior against a sit-and-wait type predator A. venator in this study. The short strain beetles were more easily orientated by predators and suffered a higher rate of predation than the long strains. The time to predation was also shorter in the short strains compared to the long strains. When the predator was starved, even the long strains were preyed upon when the predator was orientated toward the prey, suggesting the starvation period, i.e., prey density, is an important factor for antipredator behavior. Traditionally, death feigning has been thought to be the last resort in a series of anti-predator avoidance behaviors. However, our results showed that freezing and death feigning were not parts of a series of behavior, but independent behaviors against different predators, at least for these beetles. The results also suggest that the differences in feeding rates between the strains could be explained by differences in activity among the strains.

Evolution of spin freezing transition and structural, magnetic phase diagram of Dy$$_{2-\textit{x}}$$La$$_\textit{x}$$Zr$$_{2}$$O$$_{7}$$ (0 $$\le$$ $$\textit{x}$$ $$\le$$ 2.0)

Dy$$_{2}$$ 2 Zr$$_{2}$$ 2 O$$_{7}$$ 7 a disordered pyrochlore system, exhibits the spin freezing behavior under the application of the magnetic field. We have performed detailed magnetic studies of Dy$$_{2-\textit{x}}$$ 2 - x La$$_\textit{x}$$ x Zr$$_{2}$$ 2 O$$_{7}$$ 7 to understand the evolution of the magnetic spin freezing in the system. Our studies suggest the stabilization of the pyrochlore phase with the substitution of non-magnetic La along with the biphasic mixture of fluorite and pyrochlore phases for the intermediate compositions. We observed that the spin freezing (T$$_{f}$$ f $$\sim$$ ∼ 17 K) at higher La compositions (1.5 $$\le$$ ≤ $$\textit{x}$$ x $$\le$$ ≤ 1.99) is similar to the field-induced spin freezing for low La compositions (0 $$\le$$ ≤ $$\textit{x}$$ x $$\le$$ ≤ 0.5) and the well-known spin ice systems Dy$$_{2}$$ 2 Ti$$_{2}$$ 2 O$$_{7}$$ 7 and Ho$$_{2}$$ 2 Ti$$_{2}$$ 2 O$$_{7}$$ 7 . The low-temperature magnetic state for higher La compositions (1.5 $$\le$$ ≤ $$\textit{x}$$ x $$\le$$ ≤ 1.99) culminates into a spin-glass like state below 6 K. Cole–Cole plot and Casimir-du Pr$$\acute{e}$$ e ´ fit shows the narrow distribution of spin relaxation time in these compounds.

Individual Differences in Conditioned Fear and Extinction in Female Rats

The inability to extinguish a traumatic memory is a key aspect of post-traumatic stress disorder (PTSD). While PTSD affects 10–20% of individuals who experience a trauma, women are particularly susceptible to developing the disorder. Despite this notable female vulnerability, few studies have investigated this particular resistance to fear extinction observed in females. Similar to humans, rodent models of Pavlovian fear learning and extinction show a wide range of individual differences in fear learning and extinction, although female rodents are considerably understudied. Therefore, the present study examined individual differences in fear responses, including freezing behavior and ultrasonic vocalizations (USVs), of female Long–Evans rats during acquisition of fear conditioning and cued fear extinction. Similar to prior studies in males, female rats displayed individual variation in freezing during cued fear extinction and were divided into extinction competent (EC) and extinction resistant (ER) phenotypes. Differences in freezing between ER and EC females were accompanied by shifts in rearing during extinction, but no darting was seen in any trial. Freezing behavior during fear learning did not differ between the EC and ER females. Vocalizations emitted in the 22 and 50 kHz ranges during fear learning and extinction were also examined. Unlike vocalizations seen in previous studies in males, very few 22 kHz distress vocalizations were emitted by female rats during fear acquisition and extinction, with no difference between ER and EC groups. Interestingly, all female rats produced significant levels of 50 kHz USVs, and EC females emitted significantly more 50 kHz USVs than ER rats. This difference in 50 kHz USVs was most apparent during initial exposure to the testing environment. These results suggest that like males, female rodents show individual differences in both freezing and USVs during fear extinction, although females appear to vocalize more in the 50 kHz range, especially during initial periods of exposure to the testing environment, and emit very few of the 22 kHz distress calls that are typically observed in males during fear learning or extinction paradigms. Overall, these findings show that female rodents display fear behavior repertoires divergent from males.

Sexually dimorphic and asymmetric effects of embryonic ethanol exposure on hypocretin/orexin neurons as related to behavioral changes in zebrafish

Neurons expressing the neuropeptide hypocretin/orexin (Hcrt) in the hypothalamus promote reward-related behaviors including alcohol consumption and are shown in rodents and zebrafish to be stimulated by embryonic exposure to ethanol (EtOH). We used here in zebrafish three-dimensional analyses of the entire population of Hcrt neurons to examine how embryonic EtOH exposure at low-moderate concentrations (0.1% or 0.5% v/v) alters these neurons in relation to behavior. We found that EtOH in the water for 2 h (22–24 h post fertilization) increases the number of Hcrt neurons on the left but not right side of the brain through a stimulation of cell proliferation, this is accompanied by a decrease in locomotor activity under novel conditions but not after habituation, and these effects are evident in both larvae and adults indicating they are long lasting. Our analyses in adults revealed sexually dimorphic effects, with females consuming more EtOH-gelatin and exhibiting more freezing behavior along with an asymmetric increase in Hcrt neurons and males exhibiting increased aggression with no change in Hcrt. These findings suggest that a long lasting, asymmetric increase in Hcrt neurons induced by EtOH results from an asymmetric increase in proliferation specific to Hcrt and contributes to behavioral changes in females.